Bulk Comptonization spectra in blazars
| dc.creator | Celotti, Annalisa | |
| dc.creator | Ghisellini, Gabriele | |
| dc.creator | Fabian, Andrew C. | |
| dc.date | 2006-11-14 | |
| dc.date.accessioned | 2026-07-07T10:20:49Z | |
| dc.date.available | 2026-07-07T10:20:49Z | |
| dc.description | We study the time dependent spectra produced via the bulk Compton process by a cold, relativistic shell of plasma moving (and accelerating) along the jet of a blazar, scattering on external photons emitted by the accretion disc and reprocessed in the broad line region. Bulk Comptonization of disc photons is shown to yield a spectral component contributing in the far UV band, and would then be currently unobservable. On the contrary, the bulk Comptonization of broad line photons may yield a significant feature in the soft X-ray band. Such a feature is time-dependent and transient, and dominates over the non thermal continuum only when: a) the dissipation occurs close to, but within, the broad line region; b) other competing processes, like the synchrotron self-Compton emission, yield a negligible flux in the X-ray band. The presence of a bulk Compton component may account for the X-ray properties of high redshift blazars that show a flattening (and possibly a hump) in the soft X-rays, previously interpreted as due to intrinsic absorption. We discuss why the conditions leading to a detectable bulk Compton feature might be met only occasionally in high redshift blazars, concluding that the absence of such a feature in the spectra of most blazars should not be taken as evidence against matter--dominated relativistic jets. The detection of such a component carries key information on the bulk Lorentz factor and kinetic energy associated to (cold) leptons. | |
| dc.description | 8 pages; 4 figures; MNRAS, accepted | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0611439 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0611439 | |
| dc.identifier | Mon.Not.Roy.Astron.Soc.375:417-424,2007 | |
| dc.identifier | doi:10.1111/j.1365-2966.2006.11289.x | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/174974 | |
| dc.subject | Astrophysics | |
| dc.title | Bulk Comptonization spectra in blazars | |
| dc.type | text |